Constraints on the Stellar/Sub-stellar Mass Function in the Inner Orion Nebula Cluster

We present the results of a 0.5-0.9" FWHM imaging survey at K (2.2 micron) and H (1.6 micron) covering 5.1' x 5.1' centered on Theta 1C Ori, the most massive star in the Orion Nebula Cluster (ONC). At the age and distance of this cluster, and in the absence of extinction, the hydrogen burning limit (0.08 Mo) occurs at K~13.5 mag while an object of mass 0.02 Mo has K~16.2 mag. Our photometry is complete for source detection at the 7 sigma level to K~17.5 mag and thus is sensitive to objects as low-mass as 0.02 Mo seen through visual extinction values as high as 10 magnitudes. We use the observed magnitudes, colors, and star counts to constrain the shape of the inner ONC stellar mass function across the hydrogen burning limit. After determining the stellar age and near-infrared excess properties of the optically visible stars in this same inner ONC region, we present a new technique that incorporates these distributions when extracting the mass function from the observed density of stars in the K-(H-K) diagram. We find that our data are inconsistent with a mass function that rises across the stellar/sub-stellar boundary. Instead, we find that the most likely form of the inner ONC mass function is one that rises to a peak around 0.15 Mo, and then declines across the hydrogen-burning limit with slope N(log M) ~ M^(0.57+/-0.05). We emphasize that our conclusions apply to the inner 0.71 pc x 0.71 pc of the ONC only; they may not apply to the ONC as a whole where some evidence for general mass segregation has been found.Comment: Accepted for publication in the Astrophysical Journal. Preprints/tables also available at http://phobos.caltech.edu/~jmc/papers/onc

Effect of Preventive Primary Care Outreach on Health Related Quality of Life Among Older Adults at Risk of Functional Decline: Randomised Controlled Trial

Objective: To evaluate the impact of a provider initiated primary care outreach intervention compared with usual care among older adults at risk of functional decline. Design: Randomised controlled trial. Setting: Patients enrolled with 35 family physicians in five primary care networks in Hamilton, Ontario, Canada. Participants: Patients were eligible if they were 75 years of age or older and were not receiving home care services. Of 3166 potentially eligible patients, 2662 (84%) completed the validated postal questionnaire used to determine risk of functional decline. Of 1724 patients who met the risk criteria, 769 (45%) agreed to participate and 719 were randomised. Intervention: The 12 month intervention, provided by experienced home care nurses in 2004-6, consisted of a comprehensive initial assessment using the resident assessment instrument for home care; collaborative care planning with patients, their families, and family physicians; health promotion; and referral to community health and social support services. Main outcome measures: Quality adjusted life years (QALYs), use and costs of health and social services, functional status, self rated health, and mortality. Results: The mean difference in QALYs between intervention and control patients during the study period was not statistically significant (0.017, 95% confidence interval ?0.022 to 0.056; P=0.388). The mean difference in overall cost of prescription drugs and services between the intervention and control groups was not statistically significant, (-$C165 (£107; 118;$162), 95% confidence interval -$C16 545 to$$16 214; P=0.984). Changes over 12 months in functional status and self rated health were not significantly different between the intervention and control groups. Ten patients died in each group. Conclusions: The results of this study do not support adoption of this preventive primary care intervention for this target population of high risk older adults

Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor

We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach

Ionized gas at the edge of the Central Molecular Zone

To determine the properties of the ionized gas at the edge of the CMZ near Sgr E we observed a small portion of the edge of the CMZ near Sgr E with spectrally resolved [C II] 158 micron and [N II] 205 micron fine structure lines at six positions with the GREAT instrument on SOFIA and in [C II] using Herschel HIFI on-the-fly strip maps. We use the [N II] spectra along with a radiative transfer model to calculate the electron density of the gas and the [C II] maps to illuminate the morphology of the ionized gas and model the column density of CO-dark H2. We detect two [C II] and [N II] velocity components, one along the line of sight to a CO molecular cloud at -207 km/s associated with Sgr E and the other at -174 km/s outside the edge of another CO cloud. From the [N II] emission we find that the average electron density is in the range of about 5 to 25 cm{-3} for these features. This electron density is much higher than that of the warm ionized medium in the disk. The column density of the CO-dark H$_2$ layer in the -207 km/s cloud is about 1-2X10{21} cm{-2} in agreement with theoretical models. The CMZ extends further out in Galactic radius by 7 to 14 pc in ionized gas than it does in molecular gas traced by CO. The edge of the CMZ likely contains dense hot ionized gas surrounding the neutral molecular material. The high fractional abundance of N+ and high electron density require an intense EUV field with a photon flux of order 1e6 to 1e7 photons cm{-2} s{-1}, and/or efficient proton charge exchange with nitrogen, at temperatures of order 1e4 K, and/or a large flux of X-rays. Sgr E is a region of massive star formation which are a potential sources of the EUV radiation that can ionize the gas. In addition X-ray sources and the diffuse X-ray emission in the CMZ are candidates for ionizing nitrogen.Comment: 12 pages, 9 figure

Dataset Construction and Analysis of Screenshot Malware

Among the various types of spyware, screenloggers are distinguished by their ability to capture screenshots. This gives them considerable nuisance capacity, giving rise to theft of sensitive data or, failing that, to serious invasions of the privacy of users. Several examples of attacks relying on this screen capture feature have been documented in recent years. However, there is not sufficient empirical and experimental evidence on this topic. Indeed, to the best of our knowledge, there is no dataset dedicated to screenshot-taking malware until today. The lack of datasets or common testbed platforms makes it difficult to analyse and study their behaviour in order to develop effective countermeasures. The screenshot feature is often a smart feature that does not activate automatically once the malware has infected the machine; the activation mechanisms of this function are often more complex. Consequently, a dataset which is completely dedicated to them would make it possible to better understand the subtleties of triggering screenshots and even to learn to distinguish them from the legitimate applications widely present on devices. The main purpose of this paper is to build such a dataset and analyse the behaviour of screenloggers

Detection of a dense clump in a filament interacting with W51e2

In the framework of the Herschel/PRISMAS Guaranteed Time Key Program, the line of sight to the distant ultracompact HII region W51e2 has been observed using several selected molecular species. Most of the detected absorption features are not associated with the background high-mass star-forming region and probe the diffuse matter along the line of sight. We present here the detection of an additional narrow absorption feature at ~70 km/s in the observed spectra of HDO, NH3 and C3. The 70 km/s feature is not uniquely identifiable with the dynamic components (the main cloud and the large-scale foreground filament) so-far identified toward this region. The narrow absorption feature is similar to the one found toward low-mass protostars, which is characteristic of the presence of a cold external envelope. The far-infrared spectroscopic data were combined with existing ground-based observations of 12CO, 13CO, CCH, CN, and C3H2 to characterize the 70 km/s component. Using a non-LTE analysis of multiple transitions of NH3 and CN, we estimated the density (n(H2) (1-5)x10^5 cm^-3) and temperature (10-30 K) for this narrow feature. We used a gas-grain warm-up based chemical model with physical parameters derived from the NH3 data to explain the observed abundances of the different chemical species. We propose that the 70 km/s narrow feature arises in a dense and cold clump that probably is undergoing collapse to form a low-mass protostar, formed on the trailing side of the high-velocity filament, which is thought to be interacting with the W51 main cloud. While the fortuitous coincidence of the dense clump along the line of sight with the continuum-bright W51e2 compact HII region has contributed to its non-detection in the continuum images, this same attribute makes it an appropriate source for absorption studies and in particular for ice studies of star-forming regions.Comment: Accepted for publication in A&